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The propargylbenzene dimer: C-H···π assisted π-π stacking
Aniket Kundu1, Saumik Sen, G Naresh Patwari
1Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India. naresh@chem.iitb.ac.in.
Physical Chemistry Chemical Physics : PCCP
|March 12, 2015
Summary
The propargylbenzene dimer adopts a stable anti-parallel, π-stacked structure stabilized by electrostatics and dispersion. This structure is driven by a synergistic interplay of π-π stacking and C-H···π interactions.
Area of Science:
- Physical Chemistry
- Spectroscopy
- Computational Chemistry
Background:
- Understanding intermolecular forces is crucial for molecular assembly.
- Propargylbenzene (PrBz) is a molecule with potential for unique interactions.
Purpose of the Study:
- To elucidate the structure and stabilization mechanisms of the propargylbenzene dimer.
- To compare its interactions with related dimers like phenylacetylene and toluene.
Main Methods:
- Mass-selected electronic and infrared (IR) spectroscopy.
- Quantum chemical calculations, including symmetry-adapted perturbation theory (SAPT).
Main Results:
- The IR spectrum indicates an identical environment for both propargylbenzene units in the dimer.
- Calculations predict an anti-parallel structure as the most stable isomer.
- Observed spectra are assigned to π-stacked structures with C-H···π interactions.
Conclusions:
- The propargylbenzene dimer's stability arises from a combination of π-π stacking and C-H···π interactions.
- Electrostatic forces contribute approximately 35% to stabilization, with dispersion being dominant.
- The synergistic effect in PrBz dimer leads to higher stabilization compared to phenylacetylene and toluene dimers.
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